This invention pertains to aldol condensations and more particularly to the heterogeneous catalyst used for said aldol condensations.
The aldol condensation of active hydrogen containing organic carbonyl compounds has been widely used in industry for synthesize compounds. Base catalyst such as alkali metal hydroxides have been used for producing 2-ethylhexanediol-1,3, 2-ethylhexanol-1, diacetone alcohol, isophorone, mesityl oxide, methyl isoamyl ketone, methyl isobutyl ketone, and the like.
Myriad methods have been disclosed for converting, for example, acetone by aldol condensation into a variety of products particularly isophorone and mesityl oxide which are used in industrial solvents and as chemical intermediates for resins, dyes, insecticides and the like. By-products which arise from the general reaction include diacetone alcohol, 4,4-dimethyl-hepta-2,6-dione, 4,6-dimethyl-hepta-3,5-diene-2-one, 3,5,5-trimethylcyclohex-3-ene-one, mesitylene, 2,2,6,6-tetramethyl, tetrahydropyran-4-one, xylitones, and isoxylitones, as well as various unidentified high boilers and tars. Needless to say, the specificity of the reaction must be controlled for commercial success in order to direct the conversion of acetone to the desired end products.
It is an object of this invention to control the condensation of acetone to produce chiefly mesityl oxide and isophorone and in addition to limit the molar ratio of mesityl oxide:isophorone produced to a low value (preferably less than 1) to conform to the commercial demand for these 2 products.
It is another object of the invention to provide a catalyst for this control condensation of acetone having the following properties:
High and constant activity PA1 Reproducible activity PA1 Long Catalyst Life PA1 Ability to regenerate readily PA1 Consistent in selective production of mainly mesityl oxide and isophorone PA1 Cheap and available PA1 (a) interacting stoichiometric amounts of a water-soluble salt of a metal of Group II of the Deming Periodic Table and a water-soluble aluminum salt with a stoichiometric amount of an alkali metal or alkaline earth metal, water-soluble hydroxide in water to precipitate a water-insoluble slurry of mixed hydroxides with the proviso that the ratio of gram atoms of Group II metal to aluminum metal is in the range of about 0.02 to about 0.3; PA1 (b) washing the slurry from step (s) with water until substantially free of water-soluble salts; PA1 (c) contacting the washed slurry from step (b) with a dilute aqueous solution of a lithium or zinc salt at ambient temperatures; and PA1 (d) recovering and drying the product of step (c) at a temperature below about 400.degree. C. PA1 (a) interacting a stoichiometric amount of a water-soluble salt of a metal of Group II of the Deming Periodic Table with a stoichiometric amount of an inorganic water-soluble hydroxide in water to precipitate a water-insoluble slurry; PA1 (b) mixing 100 parts by weight on a dry basis of the slurry of step (a) with about 1 to about 20 parts by weight, of a water-soluble salt of a metal of Group II of the Deming Periodic Table dissolved in water to produce a second slurry; PA1 (c) mixing 100 parts by weight on a dry basis of the slurry of step (b) with about 2 to about 40 parts by weight on a dry basis of an alkali metal aluminate to afford a third slurry; PA1 (d) washing the slurry of step (c) with water until substantially free of the water-soluble salts; PA1 (e) contacting the washed slurry of step (d) with a dilute aqueous solution of a lithium or zinc salt at ambient temperatures; and PA1 (f) recovering and drying the product of step (e) at a temperature below about 400.degree. C. PA1 B = total Acetone in product PA1 Mso = total Equivalents of acetone in the mesityl oxide product PA1 I = total equivalents of acetone in the isophorone product.
Examples of typical catalysts used for the conversion of acetone to isophorone and mesityl oxide are: alkali metal hydroxides, such as, sodium, potassium, and lithium hydroxide; alkaline earth hydroxides, such as, calcium, magnesium, strontium and barium hydroxide; calcium aluminate, sodium aluminate, calcium borate, potassium zincate, magnesium plumbate, barium aluminate, lithium plumbate, sodium borate, strontium stannate, potassium stannate, calcium borate, magnesium antimonate, sodium antimonate, calcium arsenate, sodium arsenate, potassium titanate, calcium zincate, magnesium aluminate, beryllium aluminate, cesium borate, rubidium arsonate, lithium phosphate, magnesium oxide, and the like.
It is another object of this invention to provide a catalyst and method for the aldol condensation of active hydrogen containing organic carbonyl compounds in general.